diff --git a/eng/packaging.props b/eng/packaging.props
index 8c4d987de58fc7..dcaf0ba043366b 100644
--- a/eng/packaging.props
+++ b/eng/packaging.props
@@ -1,20 +1,9 @@
 <Project>
 
   <PropertyGroup>
-    <DefaultAllowedOutputExtensionsInPackageBuildOutputFolder>.dll;.exe;.winmd;.json;.pri;</DefaultAllowedOutputExtensionsInPackageBuildOutputFolder>
+    <!-- Needs to be set in a props file when package referencing NuGet.Build.Tasks.Pack, as NuGet's targets file is imported before
+         packaging.targets and hence the BeforePack isn't respected. This can be moved back when the PackageReference is removed. -->
+    <BeforePack>AddNETStandardCompatErrorFileForPackaging;IncludeAnalyzersInPackage;$(BeforePack)</BeforePack>
   </PropertyGroup>
 
-  <ItemGroup>
-    <!-- Add a marker to help the designer optimize & share .NET Core packages -->
-    <None Include="$(PackageDesignerMarkerFile)"
-          PackagePath="$([System.IO.Path]::GetFileName('$(PackageDesignerMarkerFile)'))"
-          Pack="true"
-          Condition="'$(IncludeDesignerMarker)' != 'false'" />
-  </ItemGroup>
-
-  <!-- TODO: Remove when all required nuget pack features are part of the consumed SDK. -->
-  <ItemGroup>
-    <PackageReference Include="NuGet.Build.Tasks.Pack" Version="$(NuGetBuildTasksPackVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
-  </ItemGroup>
-
 </Project>
diff --git a/eng/packaging.targets b/eng/packaging.targets
index 4da978473768b6..ecd2363fd2bef1 100644
--- a/eng/packaging.targets
+++ b/eng/packaging.targets
@@ -12,7 +12,6 @@
     <!-- Don't include target platform specific dependencies, since we use the target platform to represent RIDs instead -->
     <SuppressDependenciesWhenPacking Condition="'$(ExcludeFromPackage)' == 'true' or ('$(TargetsAnyOS)' != 'true' and $([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net5.0')))">true</SuppressDependenciesWhenPacking>
     <PackageDesignerMarkerFile>$(MSBuildThisFileDirectory)useSharedDesignerContext.txt</PackageDesignerMarkerFile>
-    <BeforePack>AddNETStandardCompatErrorFileForPackaging;IncludeAnalyzersInPackage;$(BeforePack)</BeforePack>
     <!-- Generate packages in the allconfigurations build. -->
     <GeneratePackageOnBuild Condition="'$(BuildAllConfigurations)' == 'true'">true</GeneratePackageOnBuild>
     <!-- Search for the documentation file in the intellisense package and otherwise pick up the generated one. -->
@@ -28,6 +27,19 @@
                      Condition="'$(DisablePackageBaselineValidation)' != 'true' and '$(PackageValidationBaselinePath)' == '' and '$(PackageValidationBaselineVersion)' != ''" />
   </ItemGroup>
 
+  <!-- TODO: Remove when all required nuget pack features are part of the consumed SDK. -->
+  <ItemGroup>
+    <PackageReference Include="NuGet.Build.Tasks.Pack" Version="$(NuGetBuildTasksPackVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <!-- Add a marker to help the designer optimize & share .NET Core packages -->
+    <None Include="$(PackageDesignerMarkerFile)"
+          PackagePath="$([System.IO.Path]::GetFileName('$(PackageDesignerMarkerFile)'))"
+          Pack="true"
+          Condition="'$(IncludeDesignerMarker)' != 'false'" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(AddNETFrameworkAssemblyReferenceToPackage)' == 'true'">
     <_FrameworkAssemblyReferences Include="$(MSBuildProjectName)"
                                   TargetFramework="net461" />
diff --git a/src/libraries/Directory.Build.props b/src/libraries/Directory.Build.props
index 23421981fbadfe..2e52a7ca3dfab3 100644
--- a/src/libraries/Directory.Build.props
+++ b/src/libraries/Directory.Build.props
@@ -60,7 +60,7 @@
   </ItemGroup>
 
   <Import Project="NetCoreAppLibrary.props" />
-  <Import Project="$(RepositoryEngineeringDir)packaging.props" Condition="'$(IsPackable)' == 'true'" />
+  <Import Project="$(RepositoryEngineeringDir)packaging.props" Condition="'$(IsSourceProject)' == 'true'" />
   <Import Project="$(RepositoryEngineeringDir)referenceAssemblies.props" Condition="'$(IsReferenceAssembly)' == 'true'" />
   <Import Project="$(RepositoryEngineeringDir)targetframeworksuffix.props" Condition="'$(DesignTimeBuild)' != 'true'" />
 
diff --git a/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj b/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
index 024a193525f4a1..e017d4db8bf40a 100644
--- a/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
+++ b/src/libraries/System.IO.Ports/src/System.IO.Ports.csproj
@@ -153,10 +153,10 @@ System.IO.Ports.SerialPort</PackageDescription>
   </ItemGroup>
 
   <ItemGroup Condition="'$(IsPartialFacadeAssembly)' != 'true'">
-    <!-- Just reference the runtime meta package but don't build it to avoid unintentional Build/Pack invocations. -->
-    <ProjectReference Include="..\pkg\runtime.native.$(MSBuildProjectName).proj" />
+    <!-- Just reference the runtime packages but don't build them in order to avoid unintentional Build/Pack invocations. -->
+    <ProjectReference Include="..\pkg\runtime.native.$(MSBuildProjectName).proj" BuildReference="false" />
     <!-- Make the runtime specific packages non transitive so that they aren't flowing into other projects. -->
-    <ProjectReference Include="..\pkg\runtime.*.runtime.native.$(MSBuildProjectName).proj" PrivateAssets="all" />
+    <ProjectReference Include="..\pkg\runtime.*.runtime.native.$(MSBuildProjectName).proj" BuildReference="false" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETStandard'">